Growth of α-HgI2 single crystals from physical vapor transport in an oil-bath furnace

The growth of α-HgI2 crystals from physical vapor transport in a closed ampoule immerged in a simple and economical oil-bath furnace with an external heating coil imposed is discussed. The temperatures of the source side, Tsou, of the maximum value, Tmax, and of the crystal growth side, Tcry, together with dT/dx are changed for different growth conditions. The physical properties of the as-grown α-HgI2 crystals are characterized by scanning electron microscopy, X-ray diffraction, and I–V measurements with respect to different growth conditions. It is found that the α-HgI2 crystals grown from Tsou=125 °C, Tmax=135 °C, Tcry=114 °C, dT/dx=2.6 °C/mm, and with 5 Torr inert gas inside the growth ampoule exhibit the best qualities, such as, observable facets, transparent red color, and a low density of defects and grain boundaries.